France's proud food tradition is being crushed under layers of reheated lasagne, according to a leading restaurant union that is lobbying for a new law to protect chefs who are cooking from scratch. French politicians are considering drawing up a restaurant "appellation", similar to the system already used in wine, which could only be used by outlets cooking food in-house and from fresh.

Leading the charge to open this proverbial can of worms is Synhorcat, a national union for restaurant, cafe and hotel owners. It cites a recent study that suggests a third of France's 100,000 restaurants are using "industrial products". These, it says, are not "true" restaurants. And that's before starting on the estimated 50,000 fast-food joints, from McDonald's to local kebab houses.

This debate is part of a long-held fear that, while the French "gastronomic meal" may enjoy Unesco recognition as an "intangible cultural heritage of humanity", the country has let itself go. A seedy and swelling underbelly of packaged meals and on-the-go sandwiches is weighing on the national psyche.

There are, of course, many great places to eat in Paris, but there is also talk of frozen chips and boil-in-the-bag rice becoming increasingly popular in some brasserie kitchens. "People want cheap food, and it saves some restaurants time," one Parisian waiter tells me. He doesn't want to be named. Others are keeping the side up. "All of our desserts are freshly made in-house," says Carole Londais, the owner of La Fontaine St Michel brasserie, proudly displaying a glass cabinet of sweet treats.

And he's not the only one voicing concerns. In April, the Collège Culinaire de France, led by all-star chef duo Alain Ducasse and Joel Robuchon, launched a new label named Restaurant de Qualité. The seal is aimed at artisan restaurants, which can join if they meet certain standards on product origins, freshness and diner satisfaction.

Restaurant critic Jay Rayner has previously argued that the real story in France is not the collapse of haute cuisine, but the "demise of the €15 lunch" – a sign that minimum standards have slipped. The better news, according to Didier Chenet, is that research suggests many restaurants currently using pre-prepared "industrial products" would happily switch to freshly prepared meals if it meant gaining access to an "appellation".

Do you agree with the Gallic hardliners that no true restaurant should serve pre-prepared food? If not, what's acceptable? Does it depend on the type of restaurant and the meal in question? Would you, for instance, be outraged to discover that your basket of pommes frites had done time in the brasserie's freezer?